How to handle this type of model validation in Ruby on Rails

Posted by randombits on Stack Overflow See other posts from Stack Overflow or by randombits
Published on 2010-04-18T16:24:37Z Indexed on 2010/04/18 16:33 UTC
Read the original article Hit count: 231

Filed under:

ruby-on-rails

|

activerecord

I have a controller/model hypothetically named Pets. Pets has the following declarations:

:belongs_to owner
:has_many dogs
:has_many cats

Not the best example, but again, it demonstrates what I'm trying to solve. Now when a request comes in as an HTTP POST to http://127.0.0.1/pets, I want to create an instance of Pets. The restriction here is, if the user doesn't submit at least one dog or one cat, it should fail validation. It can have both, but it can't be missing both.

How does one handle this in Ruby on Rails? Dogs don't care if cats exists and the inverse is also true. Can anyone show some example code of what the Pets model would look like to ensure that one or the other exists, or fail otherwise?

errors.add also takes an attribute, in this case, there is no particular attribute that's failing. It's almost a 'virtual' combination that's missing.

© Stack Overflow or respective owner

Related posts about ruby-on-rails

Ruby on Rails - How can I start? [closed]

as seen on Programmers - Search for 'Programmers'
I have misconception in understanding the relationship between Ruby language and Ruby on Rails Framework. Because of 'I am an absolute beginner' in web development I have no idea if I have to grasp the fundamentals of Ruby before I go with Ruby on Rails! I also want to ask who is behind both Ruby… >>> More
DES3 decryption in Ruby on Rails

as seen on Stack Overflow - Search for 'Stack Overflow'
My RoR server receives a string, that was encrypted in C++ application using des3 with base64 encoding The cipher object is created so: cipher = OpenSSL::Cipher::Cipher::new("des3") cipher.key = key_str cipher.iv = iv_str key_str and iv_str: are string representations of key and initialization… >>> More
Ruby on rails: Image downloads with Authentication/Authorization/Time outs

as seen on Stack Overflow - Search for 'Stack Overflow'
Hi Guys, I'm having few doubts on implementing file downloads. I'm creating an app where I use attachment_fu with Amazon s3 to upload files. Things are working pretty well so far on uploading side. Now its the time to start the file downloads. Here is what I need, a logged in user search and browse… >>> More
Ruby on Rails deployment, on "thin" server with lot of attachments

as seen on Stack Overflow - Search for 'Stack Overflow'
A lot of PDFs are stored inside MySQL as a BLOB field for each PDF file. The average file size is 500K each. The Rails app will stream the :binary data as file downloads, where there is a user click on the download link. Assume there is a maximum of 5 users downloading 5 PDFs concurrently, what… >>> More
Apply Behavior Driven Development to Ruby on Rails with Rspec

as seen on Internet.com - Search for 'Internet.com'
Applying the Behavior Driven Development (BDD) methodology to your Rails development takes you beyond traditional Test Driven Development. Learn how to do it with the Ruby-based BDD framework RSpec. >>> More

Related posts about activerecord

Rails & ActiveRecord: Appending methods to models that inherit from ActiveRecord::Base

as seen on Stack Overflow - Search for 'Stack Overflow'
I have a standard ActiveRecord model with the following: class MyModel < ActiveRecord::Base custom_method :first_field, :second_field end At the moment, that custom_method is picked up by a module sent to ActiveRecord::Base. The functionality basically works, but of course, it attaches itself… >>> More
Rails ActiveRecord - Best way to perform an include?

as seen on Stack Overflow - Search for 'Stack Overflow'
I have three models: class Book < ActiveRecord::Base has_many :collections has_many :users, :through => :collections end class User < ActiveRecord::Base has_many :collections has_many :books, :through => :collections end class Collection < ActiveRecord::Base belongs_to… >>> More
Getting types of the attributes in an ActiveRecord object

as seen on Stack Overflow - Search for 'Stack Overflow'
I would like to know if it is possible to get the types (as known by AR - eg in the migration script and database) programmatically (I know the data exists in there somewhere). For example, I can deal with all the attribute names: ar.attribute_names.each { |name| puts name } .attributes just… >>> More
Changing ActiveRecord attribute value in before_save hook

as seen on Stack Overflow - Search for 'Stack Overflow'
I needed to fix the encoding of an ActiveRecord attribute and decided to do it in a before_save hook. And at this point I noticed an unexpected feature. When I wanted to change the value of the attribute, simple using the attribute_name=XY did not work as I expected. Instead of that I needed to use… >>> More
Conditions with whitespaces in activerecord find

as seen on Stack Overflow - Search for 'Stack Overflow'
So i am trying to do this Order.find :all, :conditions => "org = 'test org'" what ends up firing is SELECT * FROM `orders` WHERE (org = 'test org') the whitespace in the argument gets stripped. what am i missing.. im really stumped here. please help! >>> More